U.S. patent application number 14/127142 was filed with the patent office on 2014-07-24 for organic electronic component.
This patent application is currently assigned to Max-Planck-Gesellschaft zur Foerderung der Wissenschaften e.V.. The applicant listed for this patent is Frederik Ante, Jan Blochwitz-Nimoth, Tobias Canzler, Sascha Dorok, Hagen Klauk. Invention is credited to Frederik Ante, Jan Blochwitz-Nimoth, Tobias Canzler, Sascha Dorok, Hagen Klauk.
Application Number | 20140203254 14/127142 |
Document ID | / |
Family ID | 46354302 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140203254 |
Kind Code |
A1 |
Dorok; Sascha ; et
al. |
July 24, 2014 |
Organic Electronic Component
Abstract
The invention relates to an organic electron component having a
first electrode, a second electrode, a channel layer comprising an
organic semiconducting material and a dopant material.
Inventors: |
Dorok; Sascha; (Dresden,
DE) ; Blochwitz-Nimoth; Jan; (Dresden, DE) ;
Canzler; Tobias; (Dresden, DE) ; Klauk; Hagen;
(Stuttgart, DE) ; Ante; Frederik; (Stuttgart,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dorok; Sascha
Blochwitz-Nimoth; Jan
Canzler; Tobias
Klauk; Hagen
Ante; Frederik |
Dresden
Dresden
Dresden
Stuttgart
Stuttgart |
|
DE
DE
DE
DE
DE |
|
|
Assignee: |
Max-Planck-Gesellschaft zur
Foerderung der Wissenschaften e.V.
Muenchen
DE
Novaled AG
Dresden
DE
|
Family ID: |
46354302 |
Appl. No.: |
14/127142 |
Filed: |
June 20, 2012 |
PCT Filed: |
June 20, 2012 |
PCT NO: |
PCT/EP2012/061783 |
371 Date: |
March 13, 2014 |
Current U.S.
Class: |
257/40 |
Current CPC
Class: |
H01L 51/0512 20130101;
H01L 51/0558 20130101; H01L 51/0566 20130101; H01L 51/0545
20130101; H01L 51/0562 20130101; H01L 51/0059 20130101; H01L 51/002
20130101; H01L 51/0541 20130101 |
Class at
Publication: |
257/40 |
International
Class: |
H01L 51/05 20060101
H01L051/05 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2011 |
EP |
11170946.5 |
Claims
1. An organic electronic component comprising; a first electrode, a
second electrode, a channel layer comprising an organic
semiconducting material, and a dopant material according to formula
A-B, wherein ##STR00027## and wherein R1, R, x, and y are
independently selected from the following groups: x is 0, 1, or 2;
y is 1, 2, 3, or 4; R is an aryl group; and R1 is an alkyl group or
the alkoxy group.
2. The organic electronic component according to claim 1, wherein
the dopant material is incorporated into a doping material
layer.
3. The organic electronic component according to claim 2, wherein
the doping material layer consists of the dopant material.
4. The organic electronic component according to claim 2, wherein
the doping material layer is arranged on the organic semiconducting
material.
5. The organic electronic component according to claim 1, wherein
the dopant material is incorporated into the organic semiconducting
material.
6. The organic electronic component according to claim 1, wherein
the absolute amount of the difference between the oxidation
potential of the dopant material and the reduction potential of the
organic semiconducting material is greater than about 0.5 V.
7. The organic electronic component according to claim 2, wherein
the doping material layer comprises multiple layers, including a
first partial layer and a second partial layer, wherein the first
partial layer consists of the dopant material, the second partial
layer consists of a charge carrier-transporting matrix material and
the second partial layer is arranged between the first partial
layer and the channel layer and is in contact with the first
partial layer and the channel layer.
8. The organic electronic component according to claim 1, wherein
the organic semiconducting material is an electron-conducting
material.
9. The organic electronic component according to claim 2, wherein
the doping material layer is in direct contact with the first
electrode and the second electrode.
10. The organic electronic component according to claim 1, wherein
the first electrode is configured as a drain electrode, the second
electrode is configured as a source electrode, and the component
further comprises a gate electrode and a dielectric layer, wherein
the dielectric layer is arranged between the channel layer and the
gate electrode.
Description
FIELD OF THE INVENTION
[0001] The invention relates to an organic electronic
component.
BACKGROUND OF THE INVENTION
[0002] Organic semiconductors have gained great attention in recent
years because of their low cost, the possibility of depositing them
on large surfaces and flexible substrates and the great selection
of suitable molecules. Organic semiconductors may be used in
switchable components, for example, such as transistors and in
resistors.
[0003] Of the so-called planar components, the organic transistor
is the most important component. Organic thin-film transistors
(OTFTs) in particular have been investigated and developed for many
years already. It is expected that OTFTs will be used on a large
scale, for example, in inexpensive integrated circuits for
non-contact detection marks (RFID), but also for display screen
triggering (backplane). To permit inexpensive applications,
thin-film processes are needed in general for manufacturing the
transistors. In recent years performance features have been
improved to the extent that the commercialization of organic
transistors is foreseeable. For example, there have been reports of
OTFTs of up to 6 cm2/Vs for electrons based on fullerene C60 and up
to 5.5 cm2/Vs for holes based on pentacene.
[0004] OTFTs with an arrangement of additional layers on an active
semiconductor layer have been described. The additional layers are
also designated as encapsulation layers or cover layers. For
example, double layers of pentacene and fullerene C60 have been
used to achieve ambipolar component functionality (Wang et al.,
Org. Electron. 7, 457 (2006)). In this specific case, it can be
deduced from the energy levels that there is not a technically
relevant change in the charge carrier density in the active layer.
The document US 2007/034860 A1 also describes such a structure.
[0005] The document U.S. Pat. No. 5,500,537 describes an OTFT
structure in which another layer similar to the encapsulation layer
is applied to an active layer. The active layer is a polymer layer.
The additional layer controls the conductivity of the active layer.
However, the proposed arrangement can function only in geometries
of the layers in which source/drain contacts of the component are
not arranged in direct contact with the additional layer because
otherwise high OFF currents would be unavoidable.
[0006] The document US 2006/0202196 A1 describes structures having
an encapsulation layer embodied as an electrically homogeneous
doped layer wherein a matrix material of the encapsulation layer is
the same as or similar to a material of an active layer. This means
that the mobility of the active layer and the capsule layer and
that of the capsule layer are the same or at least similar, and
that the electric conductivity of the capsule layer is even greater
than or at least equal to the electric conductivity of the active
layer in the OFF state because of the electric doping.
[0007] Charge carrier transport in thin organic layers is described
in general by thermally activated charge carrier hopping which
leads to a relatively low mobility and a strong influence of
disorder. The field mobility in OTFTs depends on the charge carrier
density in general. a relatively high gate voltage is Therefore
usually necessary to fill the localized states and to achieve a
high charge carrier mobility in the organic layers.
[0008] In addition, the required applied voltage must be very high
if charge carrier injection between an electrode and a
semiconductor is not optimal. However, this is usually the case
with interfaces between a metal and an organic material.
BRIEF SUMMARY
[0009] The object of the invention is to create an improved organic
electronic component which can be operated at a lower voltage.
[0010] This object is achieved according to the invention by a
component according to the Independent Claim 1. Advantageous
embodiments of the invention are the subject matter of the
dependent claims.
[0011] The invention includes the idea of an organic electronic
component having a first electrode, a second electrode, a channel
layer which comprises an organic semiconducting material and a
dopant material according to formula A-B (Formula (I)), wherein
##STR00001##
and where R1, R, x and y are selected independently for B from the
following groups:
[0012] x is 0, 1 or 2,
[0013] y is 1, 2, 3 or 4,
[0014] R is selected from the aryl group and
[0015] R1 is from the alkyl group or the alkoxy group.
[0016] The components R1 and R as well as the indices x and y may
be selected independently of each other for each B in the dopant
material. For the case when A is the same as B, so the dopant
material has formula B-B, the two Bs may have different
definitions.
[0017] The channel layer comprises the channel, which is also known
as the current channel or the conducting channel. The channel layer
comprises an organic semiconducting material. The organic
semiconductor material is a charge transport material for charge
carriers, for example, holes or electrons. It may be formed as a
matrix material. The term "matrix material" here means that the
material constitutes most of the layer. The matrix material
typically constitutes more than 50 vol % of the layer, preferably
more than 90 vol %. It is preferably provided that the organic
semiconducting material is an electron-transporting material.
[0018] The electrodes have a very high conductivity in comparison
with the channel layer. For example, the electrodes may consist of
the following group of materials: metal, conductive metal oxides,
conductive polymer-based mixtures or mixtures thereof. The two
electrodes are preferably free of mutual overlapping. The two
electrodes do not have any direct contact with one another, for
example.
[0019] In one embodiment of the invention, the component may be a
resistor. The channel layer here determines most of the resistance
value of the component.
[0020] In another embodiment of the invention, it is provided that
the component is an overcurrent protection device (fuse). The
switching capacity of the overcurrent protection device here is
determined mainly by the channel layer, for example, its breakdown
voltage, current and/or temperature.
[0021] In another embodiment of the invention, it is possible to
provide that the component is a transducer, for example, a strain
gauge. The channel layer here serves as a main semiconductor layer
in the component. The conductivity of the component changes when
there is a change in the properties of the organic semiconducting
material in the channel layer due to external influences.
[0022] In another embodiment of the invention, it is possible to
provide that the component is a transistor, for example, an organic
thin-film transistor (OTFT) or an organic field effect transistor
(OFET). In one embodiment the transistor may be a step-edge OFET.
Conventional step-edge transistors are known from the prior art,
for example, from Fanghua Pu et al. Applied Physics Express 4
(2011) 054203.
[0023] The transistor may comprise a first electrode, a second
electrode and a gate electrode as well as multiple layers. The
electrodes and the multiple layers of the transistor may be formed
on a substrate, for example, e.g., as thin films. It may be
provided that one or more electrodes are made available with the
substrate, for example, by means of a silicon substrate. For
example, a drain contact and a source contact, or alternatively,
the gate electrode may be formed in or on the substrate. An organic
field effect transistor of the n type is preferred.
[0024] In a preferred embodiment it is provided that the dopant
material is incorporated into a doping material layer. Additionally
or alternatively, it is possible to provide that the dopant
material is incorporated into the organic semiconducting
material.
[0025] In another refinement of the invention it is possible to
provide that the doping material layer is made of the dopant
material.
[0026] According to a preferred embodiment it is provided that the
doping material layer is arranged on the organic semiconductor
material.
[0027] According to a refinement of the invention, the amount of
the difference between the oxidation potential of the dopant
material (OP) and the reduction potential (RP) of the organic
semiconducting material is greater than approximately 0.5 V. The
absolute value of the difference between the OP and the RP is thus
either less than -0.5 V or greater than 0.5 V.
[0028] According to another refinement, it is possible to provide
that the doping material layer is formed in multiple layers. The
doping material layer may comprise a first partial layer and a
second partial layer, wherein the first partial layer is made of
the dopant material, the second partial layer is made of a charge
carrier transporting matrix material and the second partial layer
is arranged between the first partial layer and the channel layer
as well as being in contact with the first partial layer and the
channel layer.
[0029] According to another preferred embodiment, it is provided
that the doping material layer is formed in direct contact with the
first electrode and the second electrode.
[0030] According to a preferred refinement of the invention, the
first electrode is configured as a drain electrode, the second
electrode is configured as a source electrode, a gate electrode is
formed and a dielectric layer is formed between the channel layer
and the gate electrode. This embodiment relates to a transistor,
for example.
[0031] To improve the injection between the first and/or second
electrode and the channel layer, the interface between the organic
semiconductor material and the electrode and/or the electrodes may
be doped. Alternatively, the interface may be improved by means of
a thin dopant layer.
[0032] According to one embodiment, a doping material layer, which
is not the channel layer and which contains or consists of the
dopant material according to formula (I), is determined. The dopant
material here functions as an electric n-dopant for the organic
semiconducting material in the channel layer. Additional possible
exemplary uses of the dopant material according to formula (I) are
described in the following:
[0033] The doping material layer may consist exclusively of the
dopant material according to formula (I). In this case, it forms a
pure injection layer. The doping material layer may be arranged,
for example, between the channel layer and at least one of the
electrodes. It improves the exchange of charge carriers between the
channel layer and at least one of the electrodes.
[0034] Alternatively, it is possible to provide that the doping
material layer contains a matrix material and the dopant material
according to formula (I). The doping material layer in this case
forms a doped injection layer. The doping material layer may again
be arranged between the channel layer and at least one of the
electrodes, for example. It improves the exchange of charge
carriers between the channel layer and at least one of the
electrodes.
[0035] A region of the channel layer, which is doped with the
dopant material, for example, and improves the exchange of the
charge carriers between the remaining channel layer and at least
one of the electrodes is referred to as the doped injection region.
The doped injection region may be part of the channel layer but it
may also be formed as an additional doped layer.
[0036] The invention may be embodied, for example, with the
embodiments of the document US 2010/065833 A1. The organic
semiconducting material of the channel layer and the dopant
material according to formula (I) form a combination of materials
in which electrical doping of the organic semiconductor material
takes place when the two materials are combined in one layer. The
electric doping here is based on a partial charge transfer between
the two materials. In the component proposed in this embodiment of
the invention, the organic semiconducting material is present in
the so-called active layer and the dopant material according to
formula (I) is arranged outside of the channel layer but is in
direct contact with it, for example.
[0037] The arrangement of the dopant material according to formula
(I) as a top layer (encapsulation layer) in direct contact with the
channel layer results in the Fermi level of the channel layer,
which is an active layer, being modified. This means that charge
carriers are induced into the electrically undoped channel layer,
which may also be referred to as quasi-doping. The induced charge
carriers here preferably fill deep levels of the density-of-state
distribution of the active layer and are only partially available
as free charge carriers in the active layer or not at all. This has
the advantage that the field effect mobility is increased by
filling up imperfections without thereby creating additional
imperfections. In addition, the proposed embodiment reduces both
the starting voltage and the working voltage of the component,
which is designed as an organic field effect transistor, for
example.
[0038] According to a preferred refinement of the invention, the
cover layer consists of an organic doping material. In an expedient
embodiment of the invention, it is possible to provide that the
dopant material according to formula (I) in the cover layer is
incorporated into a matrix material for which the organic doping
material is not an electric dopant.
[0039] Additionally or alternatively, the invention may be embodied
with the embodiments of document US 2010/0051923 A1 in which the
dopant material is not combined with the organic semiconducting
material but instead is arranged as a very thin layer in an
interfacial region between the active layer (channel layer) and the
dielectric layer. Alternatively, the dopant material may be
arranged adjacent to the interfacial region.
[0040] With the help of the very thin layer (so-called doping
material layer which contains the dopant material), a quasi-doping
takes place in the form of an electric doping, which is based on a
partial charge transfer between the molecular doping material, on
the one hand, and the organic material of the active layer, on the
other hand, in the regions of the active layer adjacent to the
doping material layer. Imperfections in the active layer, which
result in charge carriers, namely electrons or holes, being
captured there and then reducing the mobility of the charge
carriers within the conducting channel are saturated during
operation in the conducting channel. Saturated imperfections can no
longer interfere with the flow of current in the conducting channel
within the active layer. Unsaturated imperfections result in
electrons or holes being captured, so that these charge carriers
are repeatedly captured in imperfections and released again on
their path through the conducting channel between a source
electrode and a drain electrode. This negative effect is
significantly reduced or even ruled out with this quasi-doping.
[0041] The doping material layer may be formed as a closed or a
non-closed layer. The closed or non-closed layer, which may be
formed by multiple separate subregions, for example, may be limited
to a subsection of the interfacial region. The layer thickness of
the doping material layer preferably amounts to at most one-tenth
of the layer thickness of the active layer. A doping material layer
with a thickness equal to or less than 5 nm is preferred.
[0042] The terms "energy of the HOMO" or E(HOMO) (HOMO--highest
occupied molecular orbital) and "energy of the LUMO" and/or E(LUMO)
(LUMO--lowest unoccupied molecular orbital) are usually synonymous
with the terms ionization energy or electron affinity (Koopman's
theorem). In n-doping, there is an electron transfer from the HOMO
level of the n-dopant to the LUMO level of the matrix material,
where the electron is not strongly localized but instead is counted
with the charge carriers.
[0043] According to a refinement of the invention, the amount of a
difference between the HOMO of the dopant material according to
formula (I) and the LUMO of a matrix material of the channel layer
is less than approximately 1 eV; more preferably, the amount of the
difference is less than approximately 0.5 eV.
[0044] The organic semiconducting material of the channel layer may
be an electron transporting material, for example. The material may
have a high intrinsic charge carrier mobility, for example, greater
than 10-4 cm2/Vs, preferably greater than or equal to 10-1 cm2/Vs.
The organic semiconducting material preferably has a relatively low
LUMO level of approximately 3 to 4.5 eV.
[0045] Examples of organic semiconducting matrix materials that can
be used in the channel layer include: fullerene C60 and C70 and
derivatives, e.g., PCMB, [6,6]-phenyl-C61-butyric acid methyl
ester; pentacene and derivatives; rubrene; oligothiophenes and
derivatives; phthalocyanine and metallophthalocyanine and
derivatives, mainly fluorinated metalophthalocyanines; PTCDI,
perylene tetracarboxylic diimide and derivatives, polymers, e.g.,
P3HT.
[0046] The layers can be produced, for example, by vacuum
evaporation, for example, by VTE (vacuum thermal evaporation) or
OVPD (organic vapor phase deposition). In addition, vacuum spray
methods may also be used for production. Another example of a type
of deposition includes thermally or optically induced transfer of
the material from a carrier substrate to the actual substrate, for
example, by means of LITI (laser induced thermal imaging).
Alternatively or additionally, pressure methods such as stamping,
embossing and/or stamp transfer may also be used. Doped layers are
produced in vacuo, typically by means of mixed evaporation from two
independently regulated sources for the matrix material and the
dopant. Alternatively, they may also be formed by interdiffusion
from a dopant layer into a matrix material layer situated beneath
it, wherein the two materials are vapor-deposited one after the
other in vacuo and then interdiffusion is facilitated thermally or
by means of solvents. Under some circumstances, the dopant may be
activated in the layer during or after the production process in
the layer through suitable physical and/or chemical measures, for
example, by the action of light or the action of magnetic and/or
electric fields.
[0047] Alternative production methods for the doped layers include:
[0048] Doping a matrix layer by a solution of dopants with
subsequent evaporation of the solvent, in particular by thermal
treatment. [0049] Surface doping of a matrix material layer by a
layer of dopants applied superficially. [0050] Production of a
solution of matrix molecules and dopants and then production of a
layer of the solution by means of conventional methods, for
example, evaporation of the solvent or by spin-coating.
[0051] Alternatively, the doping may also be performed by
evaporating the dopant from a precursor compound, which releases
the dopant material when heated and/or irradiated. It is
self-evident that the dopant material may also be released in the
matrix.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] The invention is explained in greater detail below on the
basis of preferred exemplary embodiments with reference to the
figures of a drawing, in which:
[0053] FIG. 1 shows a schematic diagram of the structure of a
planar component,
[0054] FIG. 2 shows a schematic diagram of the structure of an
additional planar component,
[0055] FIG. 3 shows a schematic diagram of the structure of yet
another planar component,
[0056] FIG. 4 shows a schematic diagram of the structure of an
exemplary planar component,
[0057] FIG. 5 shows a schematic diagram of the structure of an
additional exemplary planar component, and
[0058] FIG. 6 shows a schematic diagram of the structure of yet
another exemplary planar component.
DETAILED DESCRIPTION
[0059] FIG. 1 shows a schematic diagram of the structure of a
planar component with a first electrode 11, a second electrode 12
and a channel layer 14.
[0060] FIG. 2 shows a schematic diagram of another planar component
with a first electrode 21, a second electrode 22 and a channel
layer 24. An injection layer 23 is arranged between the first and
second electrodes 21, 22 and a channel 24. The injection layers may
contain the dopant material.
[0061] FIG. 3 shows a schematic diagram of the structure of yet
another planar component. The component comprises a first electrode
31, a second electrode 32 and a channel layer 34. Injection regions
33 are formed adjacent to the first and second electrodes 31, 32.
The injection regions 33 may be doped with the dopant material. The
injection regions 33 in FIG. 3a are formed as part of the channel
layer 34. FIG. 3b shows an embodiment, in which the injection
regions 33 are formed as an additional doped layer between the
channel layer 34 and the first and second electrodes 31, 32. The
additional layer comprises a semiconductor material as the matrix
material and the dopant material according to formula (I). The
additional layer and the channel layer here may comprise the same
semiconductor material.
[0062] FIG. 4 shows a schematic diagram of the structure of a
planar component having a first electrode 41 and a second electrode
42 as well as a channel layer 44. Doped injection regions 43 are
again formed on the first and second electrodes 41, 42. The channel
layer 44, the injection regions 43 as well as the first and second
electrodes are arranged on a substrate 45.
[0063] FIG. 5 shows an alternative schematic diagram of the
structure of a planar component. The component comprises a first
electrode 51, a second electrode 52, a channel layer 54 and the
doped injection regions 53. The aforementioned components are
arranged on a substrate 55.
[0064] FIG. 6 shows another alternative schematic diagram of the
structure of a planar component. The component comprises a first
electrode 61 and a second electrode 69 as well as a substrate 67.
FIG. 6 in particular shows in which regions of the component the
dopant material can be used. The dopant material may be used, for
example, in an injection layer 62, in a doped injection region 70,
in a cover layer 72, as a thin break-through channel layer 68
and/or as a thin break-through layer 64 between a gate insulator 65
and a channel layer 63. Additionally or alternatively, the dopant
material may be used in an unstructured injection layer, which
extends continuously between a source electrode and a
semiconductor, over the channel layer and between a drain electrode
and the semiconductor (extension of layer 62 not shown) and is
compensated via the channel layer (between the source and the drain
electrodes) by a layer 72. The dopant material can also be used in
the layer 71 to compensate for another dopant, for example, a
p-dopant.
[0065] The following table shows preferred exemplary compounds for
the dopant material according to formula (I).
TABLE-US-00001 ##STR00002## 1 ##STR00003## 2 ##STR00004## 3
##STR00005## 4 ##STR00006## 5 ##STR00007## 6 ##STR00008## 7
##STR00009## 8 ##STR00010## 9 ##STR00011## 10 ##STR00012## 11
##STR00013## 12 ##STR00014## 13 ##STR00015## 14 ##STR00016## 15
##STR00017## 16 ##STR00018## 17 ##STR00019## 18 ##STR00020## 19
##STR00021## 20 ##STR00022## 21 ##STR00023## 22 ##STR00024## 23
##STR00025## 24 ##STR00026## 25
[0066] Additional details regarding a few exemplary compounds are
disclosed below.
Compound 1
1,4-bis(triphenylphosphinimine)-benzene
[0067] 12.30 g (37.0 mmol) triphenylphosphine dichloride were
dissolved in 80 mL benzene, then 10 mL triethylamine and 2.0 g
(18.5 mmol) 1,4-phenylenediamine were added and the mixture was
heated for two days at reflux. After cooling, the suspension was
filtered and the precipitant was washed with a dilute sodium
hydroxide solution, followed by ethanol/water. After drying in
vacuo, 9.20 g (14.6 mmol; 79%) was obtained as a yellow solid. The
substance was purified by gradient sublimation for
characterization.
[0068] Melting point (DSC): 272.degree. C.
Compound 2
1,2-bis(triphenylphosphinimine)-benzene
[0069] 10.0 g (30.0 mmol) triphenylphosphine dichloride was
dissolved in 100 mL toluene, then 8.5 mL triethylamine and 1.62 g
(15.0 mmol) 1,2-phenylenediamine were added and the mixture was
heated for two days at 95.degree. C. After cooling, the suspension
was filtered, and the precipitate was washed with toluene. The
residue was suspended in a 2-molar sodium hydroxide solution and
stirred for 5 minutes at 45.degree. C. After filling and drying in
vacuo, 4.73 g (7.53 mmol; 50%) light yellow solids were obtained.
The substance was purified by gradient sublimation for
characterization.
[0070] Melting point (DSC): 257.degree. C.
[0071] CV (DCM): 0.29 V vs. Fc
Compound 3
1,4-bis(triphenylphosphinimine)-2-methoxybenzene
Step 1: Reduction of 2-methoxy-4-nitroaniline
[0072] 3.0 g (17.8 mmol) 2-methoxy-4-nitroaniline and 0.8 g
palladium on activated carbon (10%) were added to 100 mL
tetrahydrofuran. Then 8.7 mL (114.0 mmol) hydrazine-monohydrate was
added cautiously to 40 mL tetrahydrofuran and the reaction was
stirred for 3 hours at 90.degree. C. After cooling, the suspension
was filtered and the precipitate was washed with tetrahydrofuran.
The mother liquor was concentrated under a reduced pressure to form
a gray residue; 2.44 g (17.7 mmol, 99%) of the product was stored
under argon and used without further purification.
Step 2: 1,4-bis(triphenylphosphinimine)-2-methoxybenzene
[0073] 3.71 g (11.2 mmol) triphenylphosphine dichloride was
dissolved in 50 mL toluene under argon. A suspension of 3.1 mL
(22.3 mmol) triethylamine and 0.77 g (5.6 mmol)
2-methoxy-1,4-phenylenediamine in 50 mL toluene was added and the
mixture was heated for two days at 95.degree. C. After cooling, the
suspension was filtered and the precipitate was washed with toluene
and then suspended in a 2-molar sodium hydroxide solution and
stirred for 5 minutes at 45.degree. C., then filtered and washed
with water. After drying in vacuo, 1.96 g (2.98 mmol; 53%) brown
solid was obtained.
[0074] Melting point (DSC): 206.degree. C.
[0075] CV (DCM): -0.45 V vs. Fc (rev)
Compound 4
1,4-bis(tritolylphosphinimine)benzene
Step 1: Synthesis of tris(4-methylphenyl)phosphine dichloride
[0076] 11.7 g (49.3 mmol) hexachloroethane was added to a
suspension of 15.0 g (49.3 mmol) tris(4-methylphenyl)phosphine in
80 mL acetonitrile under argon. The mixture was stirred for 17
hours at 95.degree. C. After cooling, 200 mL dry toluene was added
and 50 mL acetonitrile was removed under a reduced pressure. The
precipitate was filtered and washed with 50 mL dry toluene and 50
mL dry hexane; after drying in vacuo, 9.83 g (53%) white solid was
obtained.
Step 2: 1,4-bis(tritoluoylphosphinimine)-benzene
[0077] A solution of 5.8 mL (41.6 mmol) triethylamine in 10 mL dry
toluene was to a mixture of 7.81 g (20.8 mmol)
tris(4-methylphenyl)phosphine dichloride at 5.degree. C. under an
argon atmosphere, then 1.12 g (10.4 mmol) 1,4-phenylenediamine was
added. The mixture was stirred for 1 hour at 110.degree. C. The
yellow precipitate was filtered out and washed with toluene and
hexane. The dry raw product was suspended in 2-molar sodium
hydroxide solution and stirred for 5 minutes at 45.degree. C. After
filtering, washing with water and drying in vacuo, 5.43 g (7.6
mmol; 73.3%) light yellow solid was obtained. The substance was
purified by gradient sublimation for characterization.
[0078] Melting point (DSC): 267.degree. C.
[0079] CV (DCM): -0.46 V vs. Fc (rev)
Compound 5
1,4-bis(tritoluoylphosphinimine)-2-methoxybenzene
Step 1: Synthesis of tritoluoylphosphine dichloride
[0080] See above
Step 2: Reduction of 2-methoxy-4-nitroaniline
[0081] See above
Step 3: 1,4-bis(tritoluoylphosphinimin)-2-methoxybenzene
[0082] 2.0 g (5.33 mmol) tritoluoylphosphine dichloride was
dissolved in 10 mL toluene under argon. A suspension of 1.5 mL
(10.7 mmol) triethylamine and 0.37 g (2.7 mmol)
2-methoxy-1,4-phenylenediamine in 15 mL toluene was added and the
mixture was heated for 18 hours at 90.degree. C. After cooling, the
suspension was filtered and the precipitate was washed with toluene
and then suspended in a 2-molar sodium hydroxide solution and
stirred for 5 minutes at 45.degree. C., then filtered and washed
with water. After drying in vacuo, 0.43 g (0.59 mmol; 22%) yellow
solid was obtained.
[0083] Melting point (DSC): 239.degree. C.
[0084] CV (DCM): -0.51 V vs. Fc
Compound 7
1,2,4,5-tetra(triphenylphosphinimine)benzene
[0085] 4.9 mL (35.2 mmol) triethylamine and 0.5 g (1.78 mmol)
1,2,4,5-tetraminobenzene tetrahydrochloride were suspended in 20 mL
acetonitrile, then 2.93 g (8.8 mmol) triphenylphosphine dichloride
was dissolved in 15 mL acetonitrile and added to the suspension at
0.degree. C. The mixture was stirred for 18 hours at room
temperature period. The suspension was filtered and the precipitate
was suspended in 2-molar sodium hydroxide solution and stirred for
5 minutes at 45.degree. C. After filtering and drying in vacuo,
0.74 g (0.6 mmol; 35%) reddish-brown solids were obtained.
[0086] Melting point (DSC): 283.degree. C.
[0087] CV (DCM)=-1.02 V vs. Fc (rev.)
Compound 8
tris(4-triphenylphospiniminphenyl)amine
[0088] 1.72 g (5.44 mmol) triphenylphosphine dichloride was
dissolved in 8 mL dichloromethane under an argon atmosphere, then
1.8 mL (12.9 mmol) triethylamine in 2 mL dichloromethane was added
slowly to the solution, then 0.5 g (1.7 mmol)
tris(4-aminophenyl)amine was added and the mixture was stirred for
4 days at room temperature. The reaction [mixture] was diluted with
dichloromethane and extracted with water. Under reduced pressure
the organic phase was concentrated. The precipitate was suspended
in a 2-molar sodium hydroxide solution and stirred for 5 minutes at
45.degree. C. After filtration and drying in vacuo, 1.50 g (1.40
mmol; 82%) solids were obtained.
[0089] Melting point (DSC): 277.degree. C.
[0090] CV (DMF): -0.39 V vs. Fc.
Compound 9
tris(4-tristoluoylphospiniminephenyl)amine
Step 1: Synthesis of tritoluoylphosphine dichloride
[0091] See above
Step 2: tris(4-tristoluoylphospiniminphenyl)amine
[0092] A solution of 3.8 mL (27.4 mmol) triethylamine in 10 mL dry
toluene was added at 5.degree. C. under an argon atmosphere to a
mixture of 3.82 g (10.2 mmol) tris(4-methylphenyl)phosphine
dichloride in 40 mL toluene, then 1.0 g (3.4 mmol)
tris(4-aminophenyl)amine was added. The mixture was stirred for a
hour at 110.degree. C. The precipitate was filtered and washed with
toluene and hexane. The dry raw product was suspended in 2-molar
setting hydroxide solution and stirred for 5 minutes at 45.degree.
C. After filtering and drying in vacuo, 3.06 g (2.6 mmol; 75%)
light-yellow solids were obtained.
Compound 11
4,4'-bis(triphenylphosphinimine)-1,1'-biphenyl
[0093] 4.15 g (12.5 mmol) triphenylphosphine dichloride was
dissolved in 30 mL benzene, then 3.4 mL triethylamine and 1.15 g
(6.25 mmol) benzidine were added. The mixture was stirred at reflux
for 3 hours. After cooling, this suspension was filtered and the
yellow precipitate was washed with dilute sodium hydroxide
solution, followed by ethanol/water. After drying in vacuo, 3.20 g
(4.66 mmol; 73%) yellow solids were obtained. The substance was
purified by gradient sublimation to characterize it.
[0094] Melting point (DSC): 283.degree. C.
[0095] CV (DCM): 0.0 V vs. Fc (rev.)
Compound 18
4,4''-bis(triphenylphosphinimine)-p-terphenyl
[0096] 2.50 g (7.5 mmol) triphenylphosphine dichloride was
dissolved in 50 mL toluene, then 2.9 mL triethylamine and 0.88 g
(3.4 mmol) 4,4''-diamino-p-terphenyl were added and the mixture was
stirred for 2 days at 95.degree. C. After cooling, the suspension
was filtered and the yellow precipitate was washed with dilute
sodium hydroxide solution, followed by water and acetonitrile,
yielding 2.06 g (2.6 mmol; 78%) light-yellow solids after drying in
vacuo. The substance was purified by gradient sublimation to
characterize it.
[0097] Melting point (DSC): 322.degree. C.
[0098] CV (DCM): 0.22 V vs. Fc (rev)
Compound 19
N4,N4''-bis(tri-p-tolylphosphoranylidene)-[1,1':4',1''-terphenyl]-4,4''-di-
amine
Step 1: Synthesis of tritolylphosphine dichloride
[0099] 11.7 g (49.3 mmol) hexachloroethane was added to a
suspension of 15.0 g (49.3 mmol) tris(4-methylphenyl)phosphine in
80 mL acetonitrile under an argon atmosphere. The mixture was
stirred for 17 hours at 95.degree. C. After cooling, 200 mL dry
toluene was added and 50 mL acetonitrile was removed under reduced
pressure. The precipitate was filtered and washed with 50 mL dry
toluene and 50 mL dry hexane, yielding 9.83 g (53%) of a white
solid substance after drying in a high vacuum.
Step 2: Synthesis of
N4,N4''-bis(tri-p-tolylphosphoranylidene)-[1,1':4',1''-terphenyl]-4,4''-d-
iamine
[0100] 1.69 g (4.5 mmol) [of what?] in 3.3 mL dichloromethane was
added to a solution of 0.52 g (2 mmol) tritolylphosphine dichloride
in 5 mL toluene. The mixture was stirred at reflux for 3 hours
after adding 1 g (10 mmol) triethylamine. The precipitate was
filtered, dried and suspended in 2-molar sodium hydroxide solution,
stirred for 5 minutes at 45.degree. C., then 0.93 g (1.1 mmol; 55%)
of a brown solid substance was obtained after filtering, washing
with water and drying in vacuo. The substance was purified by
gradient sublimation to characterize it.
[0101] Melting point: 314.degree. C.
[0102] CV (DCM): 0.18 V vs. Fc
Compound 20
N4,N4''-bis(tris(4-methoxyphenyl)phosphoranylidene)-[1,1':4',1''-terphenyl-
]-4,4''-diamine
Step 1: Synthesis of 4,4''-diazide-1,1':4',1''-terphenyl
[0103] 0.63 g (9.3 mmol) sodium nitrite in 5 mL water in 0.56 g
(9.3 mmol) urea in 5 mL water were added to a mixture of 1.2 g (4.5
mmol) [1,1':4',1''-terphenyl]-4,4''-diamine, 7.5 mL silicic acid
and 3.3 mL sulfuric acid at 0.degree. C. After stirring for 1 hour,
0.64 g (9.8 mmol) sodium azide in 5 mL water was added slowly. The
mixture was stirred for 3 hours at room temperature and then poured
onto ice. The precipitate was filtered, washed with water and dried
in vacuo, yielding 1.3 g (4.2 mmol, 93%) brown solids that were
used without further purification.
Step 2:
N4,N4''-bis(tris(4-methoxyphenyl)phosphoranylidene)-[1,1':4',1''-t-
erphenyl]-4,4''-diamine
[0104] To a solution of 0.66 g (2.1 mmol)
4,4''-diazide-1,1':4',1''-terphenyl in 15 mL toluene, we added 1.48
g (4.2 mmol) tris(4-methoxyphenyl)phosphine in 5 mL toluene under
an argon atmosphere. After 18 hours of stirring at room
temperature, the solvent was distilled off and the residue was
washed with toluene, yielding 1.70 g (1.8 mmol) yellow powder after
drying in vacuo.
[0105] Melting point: 328.degree. C.
Compound 28
N1,N4-bis(tricyclohexylphosphoranylidene)benzene-1,4-diamine
[0106] 8.1 g (34.2 mmol) hexachloroethane was added to a suspension
of 9.6 g (34.2 mmol) tricyclohexylphosphine in 60 mL acetonitrile
under an argon atmosphere. The mixture was stirred for 16 hours at
95.degree. C. After cooling to room temperature, a solution of 1.7
g (15.5 mmol) para-phenylenediamine and 11.5 mL (77.5 mmol)
2,3,4,6,7,8,9,10-octahydro-pyrimidone[1,2-a]azepine in 25 mL
acetonitrile was added. The mixture was stirred for 16 hours at
95.degree. C. and then cooled again to room temperature. The
precipitate was filtered, dried and suspended in 2-molar sodium
hydroxide solution and stirred for 5 minutes at 45.degree. C., then
5 g (7.5 mmol; 49%) of a brown solid was obtained after filtering,
washing with water and drying in vacuo. The substance was purified
by gradient sublimation to characterize it.
[0107] Melting point: 277.degree. C.
[0108] CV (THF): -0.07 V vs. Fc
Compound 29
N1,N4-bis(dimethylaminophosphoranylidene)benzene-1,4-diamine
[0109] 8.1 g (34.2 mmol) hexachloroethane was added to a suspension
of 9.6 g (34.2 mmol) tricyclohexylphosphine in 75 mL acetonitrile
under an argon atmosphere. The mixture was stirred for 16 hours at
95.degree. C. After cooling to room temperature, a solution of 3 g
(27.7 mmol) para-phenylenediamine and 20.6 mL (138.5 mmol)
2,3,4,6,7,8,9,10-octahydropyramidone[1,2-a]azepine in 15 mL
acetonitrile was added. The mixture was stirred for 16 hours at
95.degree. C. and then cooled again to room temperature the solvent
was distilled down to 20 mL. The precipitate was filtered, dried
and suspended in 2-molar sodium hydroxide solution and stirred for
5 minutes at 45.degree. C. Leaching out with toluene and washing
with ethyl acetate as well as drying in vacuo yielded 1.2 g (2.8
mmol; 10%) of a brown solid substance. The substance was purified
by means of gradient sublimation to characterize it.
[0110] Melting point: 127.degree. C.
[0111] CV (DCM): -0.61 V vs. Fc
Compound 30
N1,N5-bis(triphenylphosphoranylidene)naphthalene-1,5-diamine
[0112] 4.17 g (12.5 mmol) triphenylphosphine dichloride was
dissolved in 30 mL benzene, then 3.4 mL triethylamine and 1.0 g
(6.25 mmol) naphthalene-1,5-diamine were added and the mixture was
heated for 3 days at 80.degree. C. After cooling, the suspension
was filtered and the residue was suspended in 2-molar sodium
hydroxide solution and stirred for 5 minutes at 45.degree. C.,
yielding 2.18 g (3.21 mmol; 51%) of a yellow solid substance after
filtering and drying in vacuo. The substance was purified by means
of gradient sublimation to characterize it.
[0113] Melting point: 257.degree. C.
[0114] CV (DCM): 0.26 V vs. Fc
Compound 31
N1,N4-bis(methyldiphenylphosphoranylidene)benzene-1,4-diamine
[0115] 4.7 g (20 mmol) hexachloroethane was added to a suspension
of 4 g' (20 mmol) methyldiphenylphosphine in 25 mL acetonitrile
under an argon atmosphere. The mixture was stirred for 2.5 hours at
95.degree. C. After cooling to room temperature, a solution of 0.98
g (9.1 mmol) para-phenylenediamine and 6.3 mL (45.5 mmol)
2,3,4,6,7,8,9,10-octahydropyramidone[1,2-a]azepine in 10 mL
acetonitrile was added. The mixture was stirred for 16 hours at
95.degree. C. and then cooled again to room temperature. The
precipitate was filtered, dried and suspended in 2-molar sodium
hydroxide solution and stirred for 5 minutes at 45.degree. C.,
yielding 1.2 g (2.4 mmol; 26%) of a brown solid substance after
filtering, washing with water and drying in vacuo. The substance
was purified by means of gradient sublimation to characterize
it.
[0116] Melting point: 225.degree. C.
[0117] CV (DCM): -0.23 V vs. Fc
[0118] The intensity of the doping was determined by means of
conductivity measurements. The conductivity of a thin-film specimen
can be measured by the so-called two-point method, in which
contacts of a conductive material, for example, gold or indium tin
oxide, are applied to a substrate. Then the thin film to be
investigated is applied to the substrate over a large area, so that
the contacts are covered by the thin film. This structure
corresponds to that of a resistor. After applying a voltage to the
contacts, the current flowing through them is measured. The
resistance and/or the conductivity of the thin-film material can be
determined from the geometry of the contacts and the layer
thickness of the applied thin film.
[0119] Multiple OTFTs were produced on SiO2 substrates. To produce
an OTFT, an Al gate electrode and a gate dielectric were arranged
on the substrate. The gate dielectric may be made of 3.6 nm
aluminum oxide and 1.7 nm tetradecylphosphonium acid, for example
(Zschieschang, Adv. Mater, v. 22, pp. 982 (2010)). Then a layer of
F16CuPc with a thickness of 30 nm was arranged thereon as a
semiconductor layer. The source and drain injection layers were
deposited on the semiconductor layer. Using the same mask, a source
electrode and a drain electrode of gold were then applied, forming
an n-doped channel layer more than 1 .mu.m wide.
[0120] The multiple OTFTs were produced using various channel layer
widths, so that the contact resistance can be determined by
extrapolation. The contact resistance is 9 kOhmcm for injection
layers with a thickness of 2.5 nm, and 17 kOhmcm for injection
layers with a thickness of 5 nm. A comparative example without
doping had a contact resistance of 48 kOhmcm.
[0121] It has surprisingly been found that not only the dopant
material but also the components produced with it are stable in
air. After 50 days under a normal atmosphere, i.e., exposed to air
and ambient oxygen, the contact resistance had increased to 22
kOhmcm. This is a slight increase in comparison with the undoped
component. A comparative example with the other stronger n-dopant
resulted in an initial contact resistance of 7 kOhmcm. After 50
days under a normal atmosphere, however, the contact resistance was
already 30 kOhmcm.
[0122] Features of the present invention disclosed in the preceding
description, the claims and the drawings may be important either
individually or in any combination for the implementation of the
invention in its various embodiments.
* * * * *